Many of the recent image forming devices are constructed as printers, copiers, facsimile devices, and multifunction centers, and are integrated with a post-processing device to collaborate with each other, thereby building image forming systems.
Such an image forming system forms images on recording mediums, based on image information, and can subsequently or thereafter perform post-processing on the recording mediums, as necessary, such as punching, stapling, folding, sorting.
In order to bring such an image forming system into an operative state, in general, when a power switch provided on the image forming device side is switched on, warming-up of a fixing device of the image forming device is performed and necessary initial setting and the like are carried out through information exchange with the post-processing device. Thus, the image forming device is brought into an operative state. Likewise, the post-processing device is subjected to necessary initial setting and the like so as to be brought into an operable state for startup.
When a series of preset starting operations have been completed, information on conditions and a mode related to desired image forming is set, or information on conditions and a mode related to post-processing is set via an operation input unit provided on the image forming device or post-processing device, and thereby desired operation of image forming or post-processing is performed.
Under control of such an image forming system in a prior art, only the post-processing device is used to perform post-processing on recording mediums. However, an image forming system in a prior art enables using the post-processing device only after startup of both the image forming device and post-processing device. Accordingly, as a result of startup of both the image forming device and post-processing device, unnecessary warming-up of the fixing device of the image forming device or the like is started, and, various initial settings for forming images with the image forming device are executed. In such a manner, it is impossible to avoid waste of time taken prior to startup of the post-processor which a user wants to use quickly, and to avoid consumption of energy for wasteful power or the like.
In prior arts, in order to avoid waste of time, energy, etc. in this situation, for example, a technology is disclosed in which when power of a printing device is turned on quickly after the power of the printing device is turned off, density adjustment of the printing device is not performed, and printing operation quickly becomes available so as to shorten the time (for example, see Patent Document 1: Japanese Patent Publication TOKKAI No. 2001-96849).
Further, there is also disclosed a technology as described below (for example, see Patent Document 2: Japanese Patent Publication TOKKAI No. 2005-246870). That is, while power of an image forming device is on, power is normally supplied to respective control sections as a normal mode. However, in a case, for example, where if operation of the image forming device has not been carried out for a predetermined time and accordingly the mode turns to a sleep mode for power saving, power supply is cut off except for specific control sections and power supply systems necessary for releasing the sleep, and on the other hand, power is only supplied to a control sections and power supply system necessary for manual post-processing in a case where power supply is not necessary for the entire system, for example, for manual post-processing that allows only post-processing during execution of the sleep mode.
However, the technology disclosed in Patent Document 1 has the following problem. If power of a printing device is turned on quickly after the power of the printing device is turned off, the time between turning on and turning off of the power is short. Consequently, according to the technology disclosed in Patent Document 1, density adjustment having been set in advance before turning off the power is determined to be effective and reused. In other words, density adjustment of the printing device is not performed again after it has been once performed at the time of turning on the power, which is aimed at reduction in time so that printing can be performed quickly. Accordingly, when the power is turned on initially, it is necessary to start up the entire device to an operative state and execute density adjustment etc., wherein the technology is not aimed at a reduction in time nor waste of energy required for startup operation upon initial power-on.
In the technology disclosed in Patent Document 2, when an image forming device is moved to a sleep mode, power is only supplied to a control section and a power system necessary for performing manual post-processing, if it is not necessary to supply power to the entire system. Same as the technology by Patent Document 1, reduction in time nor waste of energy required for startup operation upon initial power-on is not achieved.
As described above, in the technologies by Patent Document 1 and Patent Document 2, even in a case where some of the devices of a system will not be used in the meantime, it is necessary to start up all the devices into an operable state by supplying power to the entire system in order to start up a device with initial power-on, causing a problem of taking time for startup operation and thus causing a waste of energy, such as power.
Considering problems including the above, an object of the invention is to provide an image forming system that reduces the time for startup of a post-processing unit when only the post-processor is to be used, and prevents waste of unnecessary power and the like so as to realize energy saving.